c#的派生类属性

Question

这个基类包含了其他类的列表

public class Blacklist
{
public int Id { get; set; }
public virtual IEnumerable<Card> Cards { get; set; }
}

Where Card class看起来像

public class Card
{
public int Id { get; set; }
public string Cuid { get; set; }
public int BlacklistId { get; set; }
}

然后我实现了一个继承黑名单类的派生类

public class BlacklistTwo : Blacklist
{
public new IEnumerable<CardTwo> Cards { get; set; }
}

CardTwo类继承了Card基类

当我试图调用一个接受基类作为派生实例参数的方法时，问题就发生了。外部类的类型是可以的，但是卡片的类型仍然作为基类实现。

的例子:

Insert(
new BlacklistTwo(){
Id = 1,
Cards = new List<CardsTwo>()
{ new CardTwo() { Id = 123123, Cuid = "123213", BlacklistId = 1}});
public void Insert(Blacklist blacklist)
{
blacklist.GetType(); // returns BlacklistTwo
blacklist.Cards.GetType(); // returns IEnumerable<Card> insted of IEnumerable<CardTwo>
}

当我将method的参数设置为dynamic时，它可以工作，但我希望尽可能避免它。

Answer 1

正如在注释中指出的那样-由于使用了'new'关键字，因此实际上并没有覆盖该属性。我想这可能就是你想达到的目的:

public interface ICard
{
int CardId { get; set; }
string Cuid { get; set; }
int BlacklistId { get; set; }
//.. Other methods and properties
}
public class Card : ICard
{
public int CardId { get; set; }
public string Cuid { get; set; }
public int BlacklistId { get; set; }
}
public class CardTwo : ICard
{
public int CardId { get; set; }
public string Cuid { get; set; }
public int BlacklistId { get; set; }
}
public class Blacklist
{
public int Id { get; set; }
public virtual IEnumerable<ICard> Cards { get; set; }
}
public class BlacklistTwo : Blacklist
{
public override IEnumerable<ICard> Cards { get; set; }
}

然后:

public Test()
{
ICard card1 = new Card();
card1.CardId = 123123;
card1.Cuid = "123213";
card1.BlacklistId = 1;
ICard card2 = new CardTwo();
card2.CardId = 123123;
card2.Cuid = "123213";
card2.BlacklistId = 1;
Insert(new BlacklistTwo()
{
Id = 1,
Cards = new List<ICard>() { card1 ,card2 }
});
if (card1 is Card c1)
{
//Yes - this is a type of Card
}

if (card2 is CardTwo c2)
{
//Yes - this is a type of CardTwo
}
}

您可以使用接口或抽象类，甚至可能避免扩展黑名单类